Unlike the requirements for an operational system, the requirements for a data warehouse are quite nebulous.
Business data is dimensional in nature and the users of the data warehouse think in terms of business dimensions.
A requirements definition for the data warehouse can, therefore, be based on business dimensions such as product, geography, time, and promotion.
Information packages—a new concept—are the backbone of the requirements definition. An information package records the critical measurements or facts and business dimensions along which the facts are normally analyzed.
Interviews and group sessions are standard methods for collecting requirements.
Key people to be interviewed or to be included in group sessions are senior executives (including the sponsors), departmental managers, business analysts, and operational systems DBAs.
Review all existing documentation of related operational systems.
Scope and content of the requirements definition document include data sources, data transformation, data storage, information delivery, and information package diagrams.